We have observed that following electron beam therapy alone (3,600 rads 6MeV) or in combination with multiple drug chemotherapy (adriamycin and cytoxan) patients with mycosis fungoides (MF) have entered prolonged periods of clinical remission with and unusual histological pattern in their resolved skin lesions. The abnormal MF cells are present without their usual accompanying inflammatory infiltrate. Because of this phenomenon, it is possible to study MF by some new approaches. The objectives of this research are to (1) perform serial karyotypes on peripheral blood lymphocytes for comparison with pretreatment karyotypes from blood and lymph nodes to answer the question how frequently and at what point in the disease does MF become a monoclonal disorder; (2) study the distribution and density of Langerhans cells, histiocytes and T-lymphocytes in cutaneous lesions before and after therapy, during clinical remissions and in the early and late stages of relapse. Such studies should provide insight into the morphological events accompanying these clinical remissions as well as the escape from these remissions; and (3) assay the patients' sera and skin lesions for the presence of an interleukin-1 like material that may be correlated with response to therapy and escape from therapy. The combination of close clinical monitoring with tests for morphologic and patho-physiological events should increase our understanding about the pathogenesis of MF and may ultimately lead to more effective therapy.